The present invention relates to an electric wire terminal material, and particularly relates to an electric wire crimp terminal material and a terminal using the terminal material.
A crimp terminal is used as an electric wire terminal such as a terminal which is excellent in connecting an electric wire to a suspender. Heretofore, a material having an Sn-plating layer provided on a base material composed of Cu or a Cu alloy such as brass is used as a material used for production of the crimp terminal. However, the terminal formed from the aforementioned material having an Sn-plating layer has a disadvantage that if the terminal is used under a high temperature for a long time, an oxide film is produced on a contact surface, that is, on a surface of the Sn-plating layer, to thereby increase contact resistance.
As a material to eliminate the aforementioned disadvantage, Japanese Patent Unexamined Publication No. Hei. 8-7960 discloses a terminal material in which in order to prevent easily oxidizable components of a base material from being diffused in the Sn-plating layer, an Ni-plating layer or a Co-plating layer is provided as an under layer, and the Sn-plating layer is provided on the under layer to thereby prevent the production of an oxide film.
The present inventors have found the following about the aforementioned terminal material having an Ni-plating layer as its under layer as disclosed in the aforementioned Publication. That is, the Ni-plating layer and the Sn-plating layer are diffused into each other to form an intermetallic compound; the intermetallic compound is easily oxidized when exposed to a high temperature; and a crimp portion of a crimp terminal formed of the material is difficult to be kept in an air-shielded contact state, so that contact resistance in the crimp portion still increases to make it impossible to eliminate the aforementioned disadvantage fundamentally. This means that the aforementioned terminal material cannot secure the long-term reliability at the terminal crimp portion.
Therefore, an object of the present invention is to provide a novel terminal material.
Another object of the present invention is to provide a terminal material suitable for a material for a crimp portion of a crimp terminal.
A further object of the present invention is to provide a terminal material capable of forming a crimp portion in which contact resistance hardly increases and long-term connection reliability is improved even in the case where the crimp portion is exposed to a high temperature for a long time.
A further object of the present invention is to provide a terminal having a crimp portion formed of the aforementioned terminal material.
The foregoing objects of the present invention can be achieved by a terminal material characterized in that a plurality of plating layers containing an Sn-plating layer as its outermost layer are provided on a base material, and when an Ni-plating layer is provided, the plating layers are formed so that the Sn-plating layer does not come in contact with the Ni-plating layer, and can be achieved by a terminal having a crimp portion formed of the terminal material.
The terminal material according to the present invention is configured so that a plurality of plating layers containing an Sn-plating layer as its outermost layer are provided, and even when an Ni-plating layer is provided, for example, a Cu-plating layer is provided between the Sn-plating layer and the Ni-plating layer so that the Sn-plating layer does not come in contact with the Ni-plating layer. Accordingly, no intermetallic compound is produced between Sn and Ni. Furthermore, oxidizable matters in the base material are prevented from being diffused into the Sn-plating layer. Accordingly, even in the case where the crimp portion of the terminal formed of the terminal material is exposed to a high temperature, the production of an oxide film at the contact portion is prevented so that the increase of contact resistance is reduced greatly.